This article discusses why it is difficult to measure the effects of management practices on organizational performance. In spite of these difficulties, a collage of evidence suggests that innovative workplace practices can increase performance, primarily through the use of systems of related practices that enhance worker participation, make work design less rigid, and decentralize managerial tasks. A majority of U.S. businesses have adopted some innovative work practices. However, only a small percentage of businesses have adopted a full system of innovative practices. We outline several constraints on the diffusion of new work practices, and suggest directions for future research